The present invention relates to axial flow type combine harvesters and, more particularly, is directed to structure for the infeed region of a combine.
In axial flow combines one or more crop handling units each provide threshing and separating regions extending longitudinally (fore-and-aft) to the direction of travel of the combine. These units generally comprise a rotor assembly rotatably mounted in a casing having a threshing concave and a separating grate. Crop material is fed to the forward or inlet end of each unit and is then urged rearwardly within the casing to effect threshing and separation whereupon separated grain is conveyed to a holding tank and the residue, i.e., chaff, straw, etc., is discharged onto the field. In one well known commercially successful axial flow combine which has become very popular in recent years, side-by-side crop handling units are mounted to receive and handle separate portions from the same swath of crop material. Exemplary of a dual unit combine of this type is the machine shown in U.S. Pat. No. 3,742,686, issued in the name of E. W. Rowland-Hill on July 3, 1973. Other prior art combines of the axial flow type have shown only one crop handling unit for handling an entire swath. Regardless of the number of units, problems in the infeed area have been encountered during operation in particular crop conditions.
Due to the nature of the threshing function, there is a relatively small clearance between the rotor assembly and the casing, thus making it inherently difficult in axial flow combines to effectively introduce large quantities of material into the threshing region of crop handling units. To enhance feeding capacity in the past, it has been found that an auger on the forward end of the rotor assembly increases effectiveness and aggressively transfers crop material from an elevator to the inlet end of the threshing region. But in certain crop conditions, an auger type infeed mechanism tends to bunch or intermittently feed dense quantities of crop material from the crop material rearwardly into the threshing region.
Bunching of abnormally thick masses of crop material at the inlet end of the threshing region, commonly referred to as "plugging", causes uneven feeding to the threshing and separating regions which if uncorrected results in inefficient operation, overloading of the threshing mechanism and undesirable power requirements. Further, bunching may cause a thumping or intense vibration of the machine structure which is generally objectionable and could result in machine damage. In extreme cases bunching of crop material may cause jamming of the rotor and even breakdown of the machine with attendant costly repairs. Still another disadvantage is potential resulting grain crackage of some crop material which has a direct effect on the price combine operators ultimately obtain.
One prior art arrangement devised to overcome the problems mentioned above is shown in U.S. Pat. No. 3,995,645, issued in the name of E. W. Rowland-Hill on Dec. 7, 1976. In this arrangement, an axial flow type combine is provided with a concave having a relief section in the forward portion of the threshing region to accommodate abnormal masses of crop material. This configuration is designed to thin out bunched material prior to passing it rearwardly in the crop handling unit.
In summary, under certain difficult crop conditions, bunching of abnormal masses of crop material at the inlet of the threshing region of crop handling units for axial flow type combines results in uneven transport of the crop, noisy operation, high peak loads on the drive means, increased power requirements, low capacities, costly repairs, etc. These disadvantages are well known to those skilled in the art of the axial flow type harvesting machine. The main purpose of the present invention is to substantially alleviate these problems in these difficult crop conditions in a manner not heretofore known by means uniformly effective in most if not all crop conditions.